moburg



Aug. 9, 19g7. 1,638,693

A. MOB URG UNDERGROUND ANTENNA Fil'ed March so, 1926- Patented Aug. 9, 1927.

UNITED STATES ALMER L. MOBURG, OF PALMS, CALIFORNIA.

uNniiReRoUNn ANTENNA.

Application filed March 30, 1926. Serial No. 98,501.

My invention is an underground antenna especially designed for radio receiving.

An object of my invention is to form a cage type of antenna and mount same in an insulating and water-proof container, such container being buried wholly or partly in wire preferably being mounted in a cylinder or drum. I

In constructing my antenna 1 utilize a cylinder with closure caps at each end and a pair of discs or spiders ateach end, the spiders having teeth or projections extending radiall over which the antenna wire is looped. T is wire is threaded with aseries of parallelstrands, being looped over the teeth or projections at the end of the discs or spiders forming substantially a cylindrical cage. Oneend of the cage is connected to a lead wire extending to a receiving or other instrument. The spiders or discs may be drawn outwardly by bolt-s to put a tension on the wire.

My invention will be more readily understood from the following description and drawings, in which;

Figure 1 is a vertical longitudinal section or my underground antenna;

Fig. 2 is a perspectiwe view of the antenna cage separated from its enclosure.

The casing or enclosure is constructed substantially as follows; there being a cylindrical body or drum 1 having closure caps 2 and 3 on the lower and upper end. These caps are preferably of similar construction each having an internal flange t forming a close fit with the cylinder. The cylinder and caps would preferably be made of insulating and waterproofing material, the caps being secured by screws or the like and the joints preferably being coated with a water-proofing composition.

The cages are built up substantially as follows: 1

An upper and 'a' lower disc or spider 5 and 6 have a series of projections or teeth 7. Each is provided with an aperture 8 extending centrally therethrough. A strut or brace 9 is positioned between the upper and lower spider and preferably has an elongated socket 10 at each end. Bolts 11 extend through the caps and through the apertures 8 in the spider and have nuts 12 on the'inside and bolt heads 13 .on the outside of the casing. The bolts are sufliciently long so that they extend into the sockets l0.

One end of the antenna wire 14 is preferably knotted or otherwise secured to one of the teeth or prongs 7 as indicated by the numeral 15 and the strands of the wire are threaded over and under the teeth or prongs on the upper and lower spiders. The end of the antenna is secured in any suitable manner to the upper spider as indicated by the numeral 16.

The nuts 12 form a tight fit in the strut 9 so that these cannot be turned but the bolt-s may be turned by means of a kerf or the like and thus draw the spiders apart, thereby placing a tension on the antenna wires. It will be understood that these wires are drawn tight in the initial threading operation and therefore the spiders will not separate to a material extent when thus drawn outwardly. The inner ends of the bolts engaging the sockets 10 of the struts 9 maintain this strut in vertical position, although it may be subject to most' compressive stresses. Any other suitable arrangement for holding the strut properly centered would be satisfactory.

An electric lead 17 extends from the end 16 of the antenna to a binding post 18 from which a lead wire 19 extends to a radio receiving set or other device.

Although my underground antenna is of .a simple character and can be made quite small. I find that quite satisfactory results areobtained with such an antenna measuring substantially 30 in. in length by 6 in. in diameter. Thisneed not be buried completely in the ground but works satisfactory with substantially one quarter exposed above the ground level.

It is obvious that the underground antenna may be considerably changed in shape or in other general features to suit particular installations, such changes however. would be within the spirit of my invention as set forth in the description, drawings and claims. 4

Having described my invention, what I claim is:

1. An underground antenna comprising in combination a substantially cylindrical casing having closure caps, a cage formed of the antenna wire in the casing, means operatively connected to the caps to stretch the cage, and an electric lead from the cage through the casing.

2. An underground antenna comprising in combination a cylindrical casing having closure caps at the top and bottom, a plurality of spiders secured to bolts, said bolts passing through the caps, the spiders having teeth on the periphery, an antenna wire secured to one of the spiders and looped in successive strands over the teeth, and an electric lead from the free end of the antenna. through one of the caps.

23. An underground antenna as claimed in claim 2, having in addition a strut with sockets therein positioned centrally between the spiders, the bolts extending into the said sockets.

lfiAn underground antenna comprising in combination a cylindrical casing of insulating material having insulated caps at the top and bottom, the joint of the caps and the casing being water-proof, a cage having disc-like spiders with teeth on the periphery, an antenna Wire secured to one of the spiders and looped over the teeth, forming successive parallel strands lengthwise of the casing, a strut centrally positioned between the spiders, the strut having sockets at opposite ends, bolts having nuts ure caps of the casing, an antenna wire stretched between said spiders and extending circumferentially around the interior of the casing, and an electric lead 'from the cage through the casing.

6. The combination of an insulating cy lindrical casing having closure caps at the top and bottom and being partly buried in the ground, a pair of disc like spiders, a central strut for positioning said spiders apart, means securing at least one of said spiders to one of the closure caps, an antenna wire secured to the periphery of each of the spiders, forming substantially parallel strands, parallel to the strut, and an electric lead from the antenna Wire extending out of'the casing.

In testimony whereof I have signed my name to this-specification.

A. L. MOBURG. 

